The present invention relates to horizontal presses for pressing fruit, and in particular grapes, comprising two concentric cylindrical cages, pervious to the juices of the fruit to be pressed and connected to rotate together, and a plate which is movable in translation and connected to rotate with the two cages so as to compress a mass of fruit disposed in the annular volume defined between the two cages and by a plate which is fixed in translation and opposite the moving plate.
An embodiment of such a press is described in French Pat. No. 1,234,355 which more particularly relates to a press in which the translation of the moving plate is obtained by means of three screws which are equally spaced apart and placed between the two cages and synchronized in rotation, the cylindrical wall of the two cages being made from perforated steel sheet. Owing, on one hand, to the existence of the centre cage whereby it is possible to discharge the juice placed in the centre which is the most difficult to extract, and, on the other hand, to the use of walls of perforated sheet in respect of which the ratio between apertures and total area is much higher than with any other method of construction, such a press has a certain number of advantages:
- THE AMOUNT OF GRAPES ADMITTED IS FROM ONE-FOURTH TO ONE-THIRD HIGHER THAN IN CONVENTIONAL PRESSES OWING TO THE HIGH FLOW OF THE JUICE DURING THE CHARGING OPERATION;
- THE EASE WITH WHICH THE JUICE ISSUES FROM THE PRESS PERMITS HIGHER PRESSING RATES;
- THE NUMBER OF OPERATIONS IS USUALLY THREE INSTEAD OF FIVE OR SIX;
- IT IS POSSIBLE TO PRESS WITHOUT DIFFICULTY THE STALKED GRAPES WHICH IS QUITE IMPOSSIBLE ON PRESSES HAVING A CAGE OF BARS WHICH ALLOWS THE ESCAPE OF MASSES OF MATERIAL THROUGH THE GAPS BETWEEN THE BARS.
However, several criticisms have been made of this press having a central juice discharge employing three screws, which are:
- FROM THE MECHANICAL AND ELECTRICAL POINT OF VIEW, THE CONSTRUCTION IS COMPLICATED AND CONSEQUENTLY COSTLY;
- THE PRESENCE OF THREE SCREWS IS SPACE-CONSUMING AND THEY ARE LIABLE TO BREAK;
- IT IS DIFFICULT TO CLEAN THE CENTRE CAGE WHICH IS ONLY ACCESSIBLE IN THE REGION OF THE DOORS OF THE OUTER CAGE.